A conventional electric synchronous motor in which permanent magnets are used to construct a rotor thereof employs methods of reducing ripples in an output torque therefrom such as using a particular shaping of each of the permanent magnets or axially separating the rotor into a plurality of rotor components and arranging these rotor components to occupy one of two positions angularly displaced from one another about an axis of the rotor.
Nevertheless, the method of using a particular shaping of the permanent magnets is unable to completely cancel torque ripples from the output torque of the motor. Further, the method of arranging a plurality of rotor components of a synchronous motor at two angularly displaced positions fails to cancel all different torque ripples having respective different cycles, except for some specific torque ripples.